Method of testing head slider and method of manufacturing head gimbal assembly

Abstract

A method includes a head-slider manufacturing process that manufactures a head slider composed of a sensor section and a slider main body. The sensor section has a tunnel magnetoresistive film and a pair of electrode films. The method further includes: a measurement process that measures a difference between an impedance between one of the electrode films and the slider main body and an impedance between the other electrode film and the slider main body; and a determination process that determines whether the difference in the impedances is within a predetermined value or not. The method further includes: a head-gimbal-assembly assembling process that assembles a head gimbal assembly by using the head slider for which it is determined that the difference in the impedances is within the predetermined value; and a HDD assembling process that assembles a HDD by using the head gimbal assembly.

1 . A method of testing a head slider mounted with a magnetoresistive head having a magnetoresistive film and a pair of electrode films sandwiching the magnetoresistive film, the method comprising:
 a measurement step that measures a difference between an impedance between one of the electrode films and a slider main body of the head slider and an impedance between the other electrode film and the slider main body; and   a determination step that determines whether the difference in the impedances is within a predetermined value or not.   
     
     
         2 . The method according to  claim 1 , wherein the magnetoresistive film is of a Tunnel-Magneto-Resistive type. 
     
     
         3 . The method according to  claim 1 , wherein the determination step determines whether the difference in the impedances is within the predetermined value or not, both in terms of absolute values of the respective impedances and in terms of phases of the respective impedances. 
     
     
         4 . The method according to  claim 1 , wherein the measurement step feeds, to the magnetoresistive film via the pair of electrode films, an alternating current of each frequency within a frequency band in which an upper limit is a frequency twice a maximum frequency in a predetermined frequency band used for detecting a magnetization direction, and
 the determination step determines whether a maximum difference in the impedances among differences in the respective frequencies is within a predetermined value or not.   
     
     
         5 . A method of manufacturing a head gimbal assembly that includes a head slider mounted with a magnetoresistive head having a magnetoresistive film and a pair of electrode films sandwiching the magnetoresistive film, the method comprising:
 a measurement step that measures a difference between an impedance between one of the electrode films and a slider main body of the head slider and an impedance between the other electrode film and the slider main body;   a determination step that determines whether the difference in the impedances is within a predetermined value or not; and   an assembly step that assembles the head gimbal assembly by using the head slider whose difference in the impedances is determined to be within the predetermined value in the determination step.